Medium optimization of neutral protease production by Bacillus subtilis ACCC 01746 in solid-state fermentationAuthor(s): YinHaicheng
The solid state fermentation (SSF) was carried out for the neutral protease production of Bacillus subtilis ACCC 01746 (B. subtilis). The fermentation factors, which included carbon, nitrogen sources and carbon-nitrogen ratio, and inorganic salts such as Na2HPO4 and KH2PO4, ZnCl2, MgCl2 and CaCl2, were investigated and optimized when wheat bran was maintained as the only constant carbon source. Maize meal and soybean meal were found best among all the carbon and nitrogen sources tested, respectively, and the ideal maize meal and soybean meal ratio is 4:3. Na2HPO4, KH2PO4 and ZnCl2 increase the protease production. In contrast, the enzyme activities were inhibited by CaCl2 and MgCl2 When these phosphates were not added in the basal SSF medium. However, MgCl2 and CaCl2 showing marginal increase at low-level concentrations and showing inhabitation at high-level concentrations.